Wittgenstein thought Leibniz’s question was unanswerable and, therefore, senseless. Asking the question was a misuse of language, sternly proscribed in the last sentence of the Tractatus:

7. Whereof one cannot speak, thereof one must be silent.

(Ironically, the sentence is often misused as meaning ‘Shut up if you don’t know what you’re talking about’, in blatant contravention of its own supposed prescription).

The riddle does not exist. This was a direct reference to Arthur Schopenhauer, who had traced the origin of philosophy to “a wonder about the world and our own existence, since these obtrude themselves on the intellect as a riddle, whose solution then occupies mankind without intermission” (The World as Will and Representation, Volume II, Chapter XVII, p. 170). Schopenhauer was himself recalling Aristotle (p. 160): “For on account of wonder (thaumazein) men now begin and at first began to philosophise” (Metaphysics, Alpha 2), and Plato (p. 170): “For this feeling of wonder (thaumazein) shows that you are a philosopher, since wonder is the only beginning of philosophy, and he who said that Iris was the child of Thaumas made a good genealogy. (Theaetetus, 155d).

There would be no riddle – said Schopenhauer – if, in Spinoza’s sense, the world were an “absolute substance“:

Therefore its non-being would be impossibility itself, and so it would be something whose non-being or other-being would inevitably be wholly inconceivable, and could in consequence be just as little thought away as can, for instance, time or space. Further, as we ourselves would be parts, modes, attributes, or accidents of such an absolute substance, which would be the only thing capable in any sense of existing at any time and in any place, our existence and its, together with its properties, would necessarily be very far from presenting themselves to us as surprising, remarkable, problematical, in fact as the unfathomable and ever-disquieting riddle. On the contrary, they would of necessity be even more self-evident and a matter of course than the fact that two and two make four. For we should necessarily be quite incapable of thinking anything else than that the world is, and is as it is (p. 170-171).

Like Parmenides, Spinoza saw non-being as inconceivable. What-is-not cannot be spoken or thought. There is only being, the absolute substance, as self-evident as 2+2=4. Schopenhauer vehemently disagreed:

Now all this is by no means the case. Only to the animal lacking thoughts or ideas do the world and existence appear to be a matter of course. To man, on the contrary, they are a problem, of which even the most uncultured and narrow-minded person is at certain more lucid moments vividly aware, but which enters the more distinctly and permanently into everyone’s consciousness, the brighter and more reflective that consciousness is, and the more material for thinking he has acquired through culture (p. 171).

Thaumazein is the origin of philosophy and the inexhaustible fount of its core, metaphysics:

The balance wheel which maintains in motion the watch of metaphysics, that never runs down, is the clear knowledge that this world’s non-existence is just as possible as is its existence. Therefore, Spinoza’s view of the world as an absolutely necessary mode of existence, in other words, as something that positively and in every sense ought to and must be, is a false one (p. 171).

Spinoza’s solution to thaumazein was straighter than Leibniz’s own. The world is not God’s contingent creation ex nihilo. It is God itself: Deus sive natura. Hence, Leibniz’s question does not even have an obvious answer. It is, as Wittgenstein put it, an unanswerable nonsense: like asking why 2+2 is 4 rather than 5. The riddle does not exist.

Nonsense – said Schopenhauer. The riddle does exist, and no solution can ever be found:

Therefore, the actual, positive solution to the riddle of the world must be something that the human intellect is wholly incapable of grasping and conceiving; so that if a being of a higher order came and took all the trouble to impart it to us, we should be quite unable to understand any part of his disclosures. Accordingly, those who profess to know the ultimate, i.e. the first grounds of things, thus a primordial being, an Absolute, or whatever else they choose to call it, together with the process, the reasons, grounds, motives, or anything else, in consequence of which the world results from them, or emanates, or falls, or is produced, set in existence, “discharged” and ushered out, are playing the fool, are vain boasters, if indeed they are not charlatans (p. 185).

Wow. So much for my faith. Notice the difference between Schopenhauer and Baloo. Baloo says: We don’t need an ultimate answer. Schopenhauer says: Of course we do. We’re not bears. Men wonder and care to know. But we can’t. As Immanuel Kant definitively demonstrated, there is no way for us to know ‘the first ground of things’ or, as he called them, things-in-themselves. All we can possibly know are phenomena – things as they appear to us, come to light and are experienced by us as evidence. Kant contrasted phenomena with noumena – things as abstract knowledge, thoughts and concepts produced by the mind (nous) independently of sensory experience. He used the term as a synonym for things-in-themselves, although – as noted by Schopenhauer (Volume I, Appendix, p. 477) – it was not quite the way the ancient Greeks used it. Be as it may, Kant’s meaning has since prevailed. Noumena are things as they are per se – unknowable to the human intellect. Phenomena are things as they appear to us as evidence through our senses. Evidence is what there is, i.e. what ex-ists, is out there in what the ancient Greeks called physis and we call, in its Latin translation, nature. Physics is mankind’s endeavour to explain the phenomena of the natural world.

As we know, however, physics’ explanations unfold into endless why-chains, which we find inconceivable. Explanations cannot go on ad infinitum: why-chains must have a last ring – an ultimate answer that ends all questions. But where can we find it, if physis is all there is?

Hence thaumazein‘s first solution: physis in not all there is. Beyond physis there is a supernatural, self-sustaining entity that created it. We know such entity not through experience but through pure reason – the logos of ancient Greeks which, like Thaumas’ daughter, Iris, links mankind to the divine. Pure reason does not require evidence. God is logically self-evident, like 2+2=4: there cannot but be one.

It was against such pure reason that Kant unleashed his arresting Critique. After Kant, whoever professes to know the Absolute earns Schopenhauer’s unceremonious epithets. Mankind cannot know the Absolute, either by experience or pure reason. It can only believe in it through revelation, leaning upon the soft evidence emanating from a trusted source, such as: ‘We believe in one God, the Father Almighty, Maker of all things visible and invisible’. Alas, the obvious trouble with such divine disclosures is their wild variety in time, place and circumstance, leaving believers with a hodgepodge of conflicting but equally conclusive revelations, imparted by self-appointed messengers employing a full bag of tricks in order to establish and support their trustworthiness.

Where does this leave us, then, with our search for the last ring? If we cannot find it in physis, where phenomena, explained by endless why-chains, are all there is, and we cannot find it beyond physis, where noumena are inaccessible to our intellect, where can we look for it? Do we need to surrender and, following Schopenhauer, declare the riddle insoluble? Do we need to heed Wittgenstein’s proscription, declare thaumazein an unanswerable nonsense and remain silent?